Implement UART flow control functionality #646
Description
in the file
https://github.com/intel-iot-devkit/mraa/blob/master/src/uart/uart.c
on function
mraa_uart_context
mraa_uart_init(int index)
...
if (!plat->no_bus_mux) {
int pos = plat->uart_dev[index].rx;
if (pos >= 0) {
if (plat->pins[pos].uart.mux_total > 0) {
if (mraa_setup_mux_mapped(plat->pins[pos].uart) != MRAA_SUCCESS) {
syslog(LOG_ERR, "uart%i: init: failed to setup muxes for RX pin", index);
return NULL;
}
}
}
The pin for rx and tx are checked if they are gpio but not the pin for CTS/RTS hardware flow control.
So we need a way to know if there are CTS/RTS pin defined in the pin config
and if you want to use the hardware flow control module the module need to configure those pins as CTS/RTS
I don't know if the best place to put this is in the init function (but we need to know the mode before the init) or in the set_flowcontrol function (or in other functions?)
mraa_result_t
mraa_uart_set_flowcontrol(mraa_uart_context dev, mraa_boolean_t xonxoff, mraa_boolean_t rtscts)
{
if (!dev) {
syslog(LOG_ERR, "uart: set_flowcontrol: context is NULL");
return MRAA_ERROR_INVALID_HANDLE;
}
if (IS_FUNC_DEFINED(dev, uart_set_flowcontrol_replace)) {
return dev->advance_func->uart_set_flowcontrol_replace(dev, xonxoff, rtscts);
}
// hardware flow control
int action = TCIOFF;
if (xonxoff) {
action = TCION;
}
if (tcflow(dev->fd, action)) {
return MRAA_ERROR_FEATURE_NOT_SUPPORTED;
}
// rtscts
struct termios termio;
// get current modes
if (tcgetattr(dev->fd, &termio)) {
syslog(LOG_ERR, "uart%i: set_flowcontrol: tcgetattr() failed: %s", dev->index, strerror(errno));
return MRAA_ERROR_INVALID_RESOURCE;
}
if (rtscts) {
termio.c_cflag |= CRTSCTS;
} else {
termio.c_cflag &= ~CRTSCTS;
}
if (tcsetattr(dev->fd, TCSAFLUSH, &termio) < 0) {
syslog(LOG_ERR, "uart%i: set_flowcontrol: tcsetattr() failed: %s", dev->index, strerror(errno));
return MRAA_ERROR_FEATURE_NOT_SUPPORTED;
}
return MRAA_SUCCESS;
}